Rust resistant lubricant composition



United States Patent No Drawing. Filed May 31, 19 63, Ser. No. 284,390 4 Claims. (Cl. 252-515) This application is a continuation-in-part of Warren Lowe and Frank A. Stuart application Serial No. 863,112 (abandoned), filed December 31, 1959, and Frank A. Stuart and Warren Lowe application Serial No. 863,113,

- filed December 31, 1959, which is now abandoned.

This invention relates to an improved rust-inhibited lubricant composition. More particularly, the invention concerns a superior new lubricating oil composition containing a unique combination of additives which inhibits rusting of ferrous metal parts under severe service conditions in internal combustion engines.

- Serious rusting problems are encountered in the operation of modern internal combustion engines. Due to the stringent conditions imposed on the engines in presentday service, more efiicient rust inhibitors are needed. Previously known additives which were adequate in preventing rusting in engines in the past under the milder operating conditions characteristic of the times are not sufficiently effective today. Furthermore, the common use of more efficient detergents in the newer lubricating oils to maintain a higher degree of cleanliness of engine parts has placed a still greater burden on the rust-inhibiting additives. This is particularly so in the case of the typical automobile high compression gasoline engines of complex design and the severe operating conditions of recent years.

It has now been found that internal combustion engine rusting problems of the most difiicult kind are successfully overcome in a lubricating oil composition comprising a major proportion of a mineral lubricating'oil and a minor proportion sufficient to inhibit rusting of the combination of a monoalkenyl succinic anhydride having 8 to 18 carbon atoms in the alkenyl group and a member of the class consisting of polymerized linoleic acid consisting essentially of a mixture of dimer and trimer acids and hydrogenated derivatives thereof, said combination containing from about to 90% by weight of the monoalkenyl succinic anhydride and from about 10 to 90% by'weight of the polymerized linoleic acid.

In another more particular embodiment of the invention, it has been further found that the above-described rust inhibited composition is surprisingly effective in the form of the more efiicient detergent lubricating oil compositions of today containing polymeric ashless detergents. Such lubricating oil compositions comprise a major proportion of a mineral lubricating oil, a minor proportion of polymeric ashless detergent suificient to enhance the detergent characteristics of said oil and a minor proportion sufficient to inhibit rusting of the combination of monoalkenyl succinic anhydride and polymerized'linoleic acid as described above.

The improved lubricating oil compositions of this invention are remarkably effective in preventing rusting of metal surfaces in internal combustion engines under severe service conditions. The lubricant compositions containing the combination of monoalkenyl succinic anhydride. and polymerized linoleic acid inhibit rusting to a surprising degree which would not be expected from the performance of either of the additives alone in similar lubricant compositions.

, The rust-inhibited polymeric ashless detergent lubricating oil compositions in accordance with this invention provide freedom from engine deposits and the accompanying Wear of engine parts, and at the same time elimstructure.

inate the aggravated rusting problems which ordinarily arise with the use of such polymeric ashless detergent oils in the operation of internal combustion engines under severe service conditions.

The polymerized linoleic acid of the lubricant composition of the invention is commercially available. It may be produced by heating the linoleic acid in the presence of water at temperatures of about 300 to 400 C. and

superatmospheric pressures, and consists essentially of a mixture of dimer and trimer. A very suitable product of this type consists approximately of by weight dimer acid and 25% by weight trimer acid. The hydrogenated polymeric linoleic acid isconveniently obtained by contacting the polymerized linoleic acid with hydrogen in the presence of a typical hydrogenation catalyst such as nickel.

The alkenyl succinic anhydride of the lubricating oil 7 composition of this invention is also available commercially. It contains from about 8 to 18 carbon atoms in v the alkenyl radical as already mentioned. Suitable alkenyl succinic anhydrides include octenyl succinic acid anhydride, decenyl succinic acid anhydride, undecenyl succinic acid anhydride, pentadecenyl succinic acid anhydride, octadecenyl succinic acid anhydride and isomers thereof having alkenyl groups of varied hydrocarbon For present purposes, the tetrapropenyl succinic acid anhydride and triisobutenyl' succinic acid anhydride utilizing propylene tetramer and isobutylene trimer as'the alkenyl groups are preferred.

The base oil in the lubricant composition of the invention is any oil of lubricating viscosity. Thus, the base oil can be a refined parafiin-type base oil, a refined naphthenic-type base oil or a synthetic hydrocarbon or synthetic nonhydrocarbon oil of lubricating viscosity. As synthetic oils, suitable examples include the hydrogenated polymers of hydrocarbons such as the polybutenes and the condensation products of chlorinated alkyl hydrocarbons with aromatic compounds such as the alkylated benzenes. Other suitable oils are those obtained by polymerization of lower molecular weight alkylene oxides such as propylene oxide and/ or ethylene oxide employing alcohol or acid initiators such as lauryl alcohol or acetic acid. Still other synthetic oils include esters, for example, di(2-ethylhexyl) sebacate, tricresyl phosphate and silicate esters such as tetra(2-ethylhexyl.) orthosilicate and hexa(2-ethylbutoxy) disiloxane. For present purposes, the mineral lubricating oils are preferred, since they show the greatest improvement in the inhibition of rusting.

As already mentioned, the lubricating oil composition of this invention contains a minor proportion of the combination of monoalkenyl succinic anhydride and polymerized linoleic acid sufficient to inhibit rusting. Usually, from about 0.05% by weight up to about 5% by weight of the combination will be sufiicient to provide excellent rust-inhibiting properties to the lubricating oil composition. The combination contains from about 10 to by weight of each of the monoalkenyl succinic anhydride and the polymerized linoleic acid compound as previously mentioned. In the prefered lubricant compositions, it is found that from about 0.1 to 3% by weight of the combination containing from about 50 to 90% by weight of the monoalkenyl succinic acid anhydride and from about 10 to about 50% by weight of the polymerized linoleic acid is most satisfactory.

The polymeric ashless detergents which are used in the lubricating oil compositions in accordance with a particular embodiment of the present invention are macromolecular materials effective in suspending and stabilizing deposit-forming materials. They are not only capable of providing a high degree of cleanliness inspark ignition automobile engines, but have the further advantage of forming no objectionable ash unlike, many of the metal'salt detergents commonly employed in lubricating oil compositions of recent years.

Suitable polymeric ashless detergents for present pur-.

poses are copolymers of (A) at least one oil-solubilizing monomer having a single ethylenic linkage and containing a monovalent hydrocarbon group of 4 to 30 aliphatic carbon atoms and (B) at least one polar monomer selected from the group consisting of unsaturated aliphatic; monoand di-carboxylic acids of 3 to 6 carbon atoms, hydroxy and aminoalkyl esters, amides and amine salts of the aforesaid unsaturated acids in which the hydroxy and aminoalkyl group contains not more than 8 carbon atoms, esters of such acids and polyalkylene glycols and alkyl ethers thereof and heterocyciic nitrogen-contained monomers such as the N-vinyl pyrrolidones.

The oil-solubilizing monomer portion (A) of the macromolecular polymeric materialsas described aboveiis .poylmerizable through the ethylenic linkage and the aliphatic hydrocarbon group, provides oil solubility.v Such oilsolubilizing monomers may be represented by the follow-Z ing general formula:

R i ')n'cH; G nR2 in which R and R are members of the group consisting of hydrogen and hydrocarbon radicals of frorn 4 to 3U carbon atoms, at least one of which contains analiphaticr hydrocarbon group of from 4 to 30 carbon atoms as described above, G and G are members of the-class consisting'of oxy (--O),.

0 0. I o carbonyl (-3-) and carbonyloxy (-JL-O or O groups andcombinations thereof with not more than two of'the present invention include the following:

OLEFINS Hexene-l Z-ethylhexene-l Diand triisobutylene Tripropylene Dodecene-l Hexadecene-l Cycloh'exene OCtadece ne-I' I 4-octylcyclohexene-l I 3-phenylhexadecene-1 p-Octyl styrene Vinyl cyclohexane 2-hexadecylbutadiene-l,3

p-Tert.butyl styrene 'ESTERS Vinyl nbutyl ether I Vinyl Z-ethylh'exy ether Allyl n-butyl ether Allyl isobutyl ether Allyl cyclohexyl ether I Allyl 4,4,8,S-tctramethyldocosyl ether Mcthallyl n-hexyl ether I Methallyl n-dccyl other Methallyl 2-ethylhexyl clhcr Vinyl caproate Vinyl palmitate Vinyl ol'eate depositv when they happen Q to be consumed in the combustion chamber of the engine,

Allyl caprylate. Allyl laurate Allyl oleate Allyl palmitate Allyl stearate vAllyl 2-ethyl hexanoate V Allyl ricinoleate Allyl esters of babassu acids Allyl esters of lard acids Allyl naphthenatc Methallyl caproate 'Methallyl naphth'enate Methallyl ricinoleate "Methallyl p-octyl benzoate Metha'llyl oleate I Methallyl cyclohexane carboxylate Methallyl palmitate Crotyl oleate Croytl naphthenate a-Methylcrotyl palmitate l-propenyl naphthenate 1-propenyl elsidate Dodecyl acrylate Hexadecyl methacrylate lsobutyl a-decyl acrylate Vinyl p-n-octyl benzoate Allyl 3,5-diisobutyl benzoate Cyclohex'yl methacrylate Methallyl octadecyl ether Propenyl 2ethylhexyl ether Crotyl n-octyl ether- Isopropenyl dodecyl ether I ldecenyl butyl ether 1'-eicosenyl decyl ether Vinyl p-octylphenyl ether Methallyl p-tert.butylphenyl ether l-decenyl p-cetylphenyl ether I l decenyl 2-phenylbutyl ether Cyclohexyl 2-dodecenoate Decyl vinyl acetate Isooctyl wchloroacrylate p-Isoamylphenyl 2-hexadecenoate 4-p-tolylbutyl 2-octadecenoate Undecyl cinnamate Methylcyclohexyl 2-ethyl-2-hexen0ate S-ethyldbc'osyl crotonate Octadecyl isocrotonate n-Butyl-Z-eicosenoate I p-Tert.amylphenyl octadecyl rnaleate I p-Hexadecylphenyl Z-ethylhexyl. maleate o-Tolyl Z-Octadecylcyclohexyl m'aleate o-Nonylphenyl hexadecyl maleate Dihexadecyl maleate I Dimethylcyclohexyl maleate Mono-,Z-ethylhexyl maleate Di-2-ethylhexyl maleate Di-dodecyl maleate I Di-dodecyl mesacronate Di-dodecyl citraconate o-Tolyl octadecyl itaconate Mono-hexadecyl itaconate Isopropenyl. palmitoleate l-clecenyl laurate l-hexadecenyl myristate Although any of the oil-solubilizing compounds described above will give etl'ective copolymer composition for lubricant compositions in accordance with the present invention, higher alkyl esters of a,fl-iinsaturated monocnrbm ylic acids of from 3 lo 6 carbon atoms having alkyl'groups or from 4 to 30 carbon atoms are most me- I tcrcd, both for-availability and etlectivencss of copolymcrs repared from them. Representative acids of this type are the acrylic, methacrylic, crotonic, tiglic, angelic, a-ethylacrylic, a-methylcrotonic, a-ethylcrotonic, fl-ethylcrotonic, fi-propylcrotonic, and hydrosorbic acids and the like. Even more desirable are the alkyl esters of acrylic and methacrylic acids containing from 8 to 18 carbon atoms in the alkyl groups, since they are found to proa major proportion of a mineral lubricating oil, a minor proportion sufiicient to enhance the detergent characteristics of said oil of the copolymer of (A) alkyl esters of unsaturated monocarboxylic acids of 3 to 6 carbon vide highly superior polymers for the lubricant composi- 5 atoms containing 4 to 18 carbon atoms in the akyl group, tions of the invention and are obtainable in commercial and (B) an N-vinyl pyrrolidone, said copolymer having quantities. 1 a molecular weight of at least about 20,000 and contain- The polar acting (B) monomers of the above descriping from about 40 to about 97 mole percent of (A) vtion include such unsaturated carboxylic acids as acrylic monomer and from about 3 to about 60 mole percent of acid, methacrylic acid, tiglic acid, maleic acid, itaconic 1 (B) monomer, and a minor proportion sufficient to inacid, mesaconic acid, and the like. For present purposes, hibit rusting of the combination of a monoalkenyl sucacrylic acid and methacrylic acid are-preferred for their cinic anhydride having 8 to 18 carbon atoms in the availability and effectiveness. alkenyl group and a member of the class consisting of The polyalkylene glycols and alkyl ethers thereof empolymerized linoleic acid consisting essentially of a ployed to form the corresponding esters of the unsaturated mixture of dimer and trimer acids and hydrogenated monoand dicarboxylic acid as (B) monomers in accordderivatives thereof, said combination containing from ance with the above description range in molecular weight about 10 to 90% by weight of the monoalkenyl succinic from about 150 to about 30,000, and preferably from anhydride and from about 10 to 90% by weight of the about 200 to 10,000. Each polyglycol is preferably linked polymerized linoleic acid. by a single ester group to the acid. Polyethylene glycols 20 The ashless polymeric detergents of the compositions and poly-1,2-propylene glycols and their alkyl ethers are according to the invention have apparent molecular preferred forpresent purposes. Such polyalkylene glycol I weights in the range from about 2,000 to as high as about materials are produced in accordance with methods known 1,0 as delelmined by the Standard light Scattering in the art. methods (see, for example, DAlelio in,Fundamental Suitable materials within the scope of the (B) mono- Princi les of Polymerization," Wiley & Sons, 1952, ppmers as mentioned above include two different types of '356-267). For practical purposes, molecular weights of materials, namely, the unsaturated heterocyclic compounds f om b t 100,000 to about 1,000,000 are most Suitablesuch as the N-vinylpyrrolidones and the aliphatic hydroxy- The preparation of the ashless polymeric detergents I and aminoalkyl esters and the hydroxyand aminoalkyl is entirely straightforward and is carried out by convenamides and amine salts of the unsaturated carboxylic tional polymerization reactions of the aforementioned acids. Suitable N-vinyl pyrrolidones are, 'for instance, (A) and monomef's- Suitable lillocedllres include 3-methyl-l-vinyl pyrrolidone, 3,3,5-trimethyl-1-viny1 pyrbulk and solution or emulsion polymerizations with the rolidone, etc. Suitable hydroxyand aminoalkyl ester, aid of suitable polymerization initiators or catalysts. amide and amine salt groups include those having the Preferably, the polymerization is elfected in an inert or- ,f ul ganic solvent medium such as benzene, using a free radical type initiator in amounts which may range from and 0.1 to 10% by weight. Suitable free radical initiators include benzoyl peroxide, one'-azodiisobutyronitrile, and in which R is thealkylene group attached to the Oxygen and similar known catalysts. Polymerization temperaor nitrogen of the ester, amide .or amine salt and R tures may range from about 200 to 400F. and R" are alkyl or hydrogen groups, the total number In further illustration of the invention, the following of carbon atoms in the alkylene, and alkyl groups is not examples are submitted showing a number of suitable more than 8. Illustrative monomers of the aforemenlubricating oil compositions. The proportions are on a tioned types include 2-hydroxyethyl, methacrylate, N, weight basis, unless otherwise specified. N-diethylaminoethyl methacrylate, 2-aminoethyl acrylate, In the examples, a variety of suitable base oils is di-Z-aminoethyl ma leate, N,N-dimethylaminohexyl acryshown. Oil A is a solvent-refined, wax-free SAE 30 late, Z-aminoethyl methacrylamide, the octyl ester of grade mineral oil lubricating oil having a viscosity index Z-aminoethyl malearnic acid, 2-hydroxyethyl methacrylof 85, which is derived from California waxy crude. amide, di(2-hydroxyethyl) maleamide, 2-hydroxyethyla- Oil B is a 140 neutral mineral lubricating oil'from solmine methacrylate, the di(2-hydroxyethylamine) maleate vent-refined waxy California crude. Oil C is a monoformed when ethanolamine is reacted with methacrylic lauryl ether of polyethylene glycol having a molecular acid and maleic acid to form the corresponding amine weight of about 400, and Oil D is di(2-ethy lhexyl) sebalt, cate, the latter two being typical synthetic base oi-ls. Another particular version of the compositions of the For convenience, the various compositions are listed invention lies in a lubricating oil composition comprising 5 in tabular form.

Table! Ratio 1) Mono- Alkenyl Llnoleic Ex. Base Polymeric Detergent mor to (2) Mono- Suecinlc Acid No. Oil mer Anhydride, Polymer,

Monomer, Etc. percent percent 1 23% (1) frl fiifififi lifiiiiii 'imamas:} 20/1 2 A"... 2.8% (l) Dodecylmethacrylnte (2) Allyl stearate 20/1/1 0.1 0.1 (3) Maleic anhydrldo fte 3 8iiif$?fii1i2ikli?n mteammates:} 7/1 4 30% $12390 i'fii liiicl ilis E5? nimd'oiec mmfiotmassa es:- 1W1 lone glycol methacrylate; 6 A".-. 2.5% 1) Allylsteurate E5; iiiflilifixwfiiiiasaaaaasms' 1 /2 0. 1 0.1

an] of in ofiggorglgcyl malcute. G 28% El? ltt% 1ilad 1511 M Table Il-Conlinucd Base Oil Polymeric Detergent No.

Ratio (1) Monomr-r to( 2) M0110 mcr to (3) Monomer, Etc.

Linoloic Acid Polymer,

percent Alkenyl Suceluic Anliydrid percent malcate. (3) Mono-N ,N -d i (Z-hydroxy-ethyl) ethylcno-diamine malcate (salt). 2.8% (l) Oct-adecene (2) .Monododocyl maleato... (3) Monopcntaery thritol maleate 2.8% (1 r l (2 Dorlecylmethacrylate" (3 Methacrylic acid (4 Monododecyl ether of eicosacthylene ycol nletlmcrylate. 2.8% (I;

gl Di-Z-ethylhexyl iumuratc (2 Octnvlecenc-l (3) Crutonic acid (4) Monotrldecyl other of decaetllylono glycol methacrylatc. I 2.8% (l) Allyl ethyl ether (2) Vinyl staccato--- (3; Itaconic acid. (4 Monododeeyl other of decucthylcne glycol crotonutc. 3.0% (1) Vinyl lrethylhexyl etheL;

(2) Tetradecylphenyl maleatc (3 Dodecyl maleatc (4 Malcic acld 1.5% (l) Dodecyl acrylate (2) Monododecyl other of dccaethylene glycol acrylate.

(3; Acrylic acid 1.5% (l Hexadecyl styrene-.. (2) Methacrylic acid.-." 1.5% (1) Butylmethucrylate (2) 'Irldecylmetlmcrylatm.

(3; Octadccyl methucrylate.- (4 3-methyl-l-vinyl pyrrolidone zaps sh I Tetra ropenyl succinlc anhdridc. X Linoleic acid dimer. b Triiso utenyl succlnic anhydride.

7 Octenyl succinic anhydridc.

The polymeric detergents which are employed in an.

embodiment in the invention as illustrated by the-above examples'are characterized by sufiicient, (A) monomer content to provide oil solubility, that is, at least about 0.1% by weightof the polymer .in oil and suflicient (B) polar monomer content to give surface-active properties to the .polymer macromolecule as'a whole. Excellent detergent characteristics are provided by from about 40. i

to about 97' mole percent of the (A). monomers and from about 3 to about 60 mole percent of the (B) monomers in copolymers of the above-mentioned types.- In

general, satisfactory detergent properties are imparted to lubricating oils by amountsfrom about 0.1 to about 10% by weight of the polymers.

Lubricant compositions within the scopeof the present inventionmay also contain still other additives of conventional types such as. pour point dcpress'ants,-oiliness and extreme pressure agents,-anti-oxidants, bloom ing agents, viscosity index improvers, and the like. Other types of detergents, such as metal salts, may also be employed where ash formation is not a problem.

Illustrative lubricant compositions of the aforemen I tioned types containing additives other than the polymeric detergents with the combination rust inhibitor may include, for example, from about 0.1 to about 10% by weight of alkaline earth metal higher alkyl phenate detergent and wear reducing agents such as the calcium alkyl phenate having mixed alkyl groups of 12 to 15 carbon atoms.

They may also include from about 0.1 to 10% by weightr Dlmerized linoleic acid (85:15 di I Hydrogenated dimerized linoleic acid.

Y a u u 99 P mer: trimer).

' dithiophosphate. Viscosity index improving agents which may be employed, usuallyin amounts oi from about 1- to 10% by Lweight, include by way of example the homopolymers of alkyl methacrylate such as the tdodecyl.

, methacrylate polymer known to the trade as Acryloid 710 and Acryloid 763, products of Rohm & Haas Com pany, and high molecular weight butane polymer such as Paratonc-ENJ 15P, aproduct of Enjay Company. Metal .saltdetergents in amounts from about 0.1% to 10% which may also be used arethe calcium petroleum sulfonates of the oil-soluble mahogany type and thec'alcium naphthenates. I 4 The lubricant compositionsof the invention also'take the form of lubricating oil concentrates suitable for blending operations in the production of compositionof the aforementioned types. Such concentrates contain as much as 20% of the combination rust inhibitor'and up to 60% of the polymeric ashless detergents or other additives whenthey are present.

Typical lubricating oil compositions in accordance with the present invention are tested in the standard LS-S Test Procedure, which has also been termed the Powerglide Rust Test.. In this test,a 6-cylinder Chevrolet (1957) engine is operated on the lubricating oil composition.;yThe.iacket temperature of the engine varies from to F.,- the oil sump temperature is F., and the engine is operated at 1500 r.p.m. for 12 hours. At the end of the test period, .the hydraulic ivalve lifters in the engine, which are extremely sensitive to rusting, are

rated on a scale of from 0 to 10, in which 0 is perfectly clean and 10 is heavy rust.

The results of a number of tests are given in Table II Tetra- Trilsobutonyl Hydrogenated Power- Ex. propenyl succinic Dlllnolelc linoleic glide N 0. Oil succinic anhydride, acid, Wt. acid, Rust anhydride, Wt. Percent Percent Wt. Percent Rating Wt. Percent 17 Ashless detergent polymer com- 8 pounded oil (E). de 2.

Ashless detergent polymer com- 7 pounded oil (F). 31 d0 0.125 0. 05 0.5 32 Ashless detergent polymer com- 0.125 0. 05 0. 1

pounded oil (G).

In the oils listed in the above table, compounded ashless detergent polymer lubricating oil (E) contains 3.2%

of a copolymer of (1) dodecyl mcthacrylate, (2) tridccyl I methacrylate, (3) octadccyl mcthacrylate and (4) polyethylene glycol monomethacrylate (1800 mol. wt.) having a ratio of alkyl methacrylate to pol'yglycol methacrylate of about 100:1 and a molecular weight of about 350,000. Oil (G) contains 2% by weight of an approximately 350,000 molecular weight copolymer of dodecyl methacrylate, octadecyl methacrylate, polyethylene glycol monomethacrylate (1800 mol. wt.) and glycidyl methacrylate in 37/17/1/1 mole ratio in which the glycidyl methacrylate is reacted with N-methyl piperaz'ine. The oil also contains the thiophosphate inhibitor (15 mM./ kg.) as mentioned above and polylauryl methacrylate and polybutcne (Paratone N) viscosity index improvers. The base oils are solvent refined SAE 10 grade mineral lubricating oils.

It will be seen from the test results in the above table that the lubricating oil compositions according to. the invention are effectively inhibited against rusting under severe service conditions. The test results also show that the combination of alkenyl succinic anhydride and polymerized linoleic acid is remarkably more effective than large amounts of either of the additives alone.

We claim:

1. A lubricating oil composition consisting essentially of a major proportion of a mineral lubricating oil and a minor proprtion sufiicient to inhibit rusting of the combination of monoalkenyl succinic acid anhydride having 8 to 18 carbon atoms in the alkenyl group and a member of the class consisting of polymerized linoleic acid consisting essentially of a mixture of dimer acid and trimer acid. and; hydrogenated polymerized linoleic acid, said combination containing from about 10 to about 90% by weight of the monoalkenyl succinic acid anhydride and from about 10 to about 90% by weight of the polymerized linoleic acid.

2. A lubricating oil composition consisting essentially of, a major proportion of a mineral lubricating oil, from sisting essentially of a mixture of approximately to by weight of dimer acid and approximately 15% to 25% by weight of trimer acid and hydrogenated polymerized linoleic acid, said combination containingfrom about 50 to about by weight of the monoalkenyl succinic acid anhydride and from about 10 to about 50% by weight of the polymerized linoleic acid, and said polymeric ashless detergent being selected from the group consisting of (1) the copolymer of butyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, and N-vinyl pyrrolidone having a ratio of alkyl methacrylate to pyrrolidone of about 10:1 and a molecular weight of approximately 250,000, and

(2) the copolymer of dodecyl methacrylate, tridecyl methacrylate, octadecyl methacrylate, and polyethyl- 1 ene glycol monomethacrylate having a ratio of alkyl methacrylate to polyglycol methacrylate of about :1 and a molecular weight of about 350,000.

3. A lubricating oil composition according to claim 2 in which the monoalkenyl succinic acid anhydride is L tetrapropenyl succinic acid anhydride.

4. A lubricating oil composition according to claim 2 in which the polymerized linoleic acid is hydrogenated polymerized linoleic acid.

References Cited by the Examiner UNITED STATES PATENTS 2,124,628 7/38 Moser 252-56 2,631,979 3/53 McDermott 252 s7 2,741,597 4/56 Oosterhoutetal 25256 2,998,414 8/61 West et al. 252-56 x 3,013,975 12/61 Stoker 252-56 XR FOREIGN PATENTS 808,665 2/59 Great Britain. 822,620 10/59 Great Britain.

DANIEL E. WYMAN, Primary Examiner. 

2. A LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A MEINERAL LUBRICATING OIL FROM ABOUT 0.1 TO ABOUT 10% BY WEIGHT OF POLYMERIC ASHLESS DETERGENT AND FROM ABOUT 0.05 TO ABOUT 5% BY WEIGHT OF THE COMBINATION OF MONOALKENYL SUCCINIC ACID ANHYDRIDE SELECTED FROM THE GROUP CONSISTING OF TETRAPROPENYL SUCCINIC ACID ANHYDRIDE AND TRIISOBUTENYL SUCCINIC ACID ANHYDRIDE IN COMBINATION WITH A MEMBER OF THE CLASS CONSISTING OF POLYMERIZED LINOLEIC ACID CONSISTING ESSENTIALLY OF A MIXTURE OF APPROXIMATELY 75% TO 85% BY WEIGHT OF DIMER ACID AND APPROXIMATELY 15% TO 25% BY WEIGHT OF TRIMER ACID AND HYDROGENATED POLYMERIZED LINOLEIC ACID, SAID COMBINATION CONTAINING FROM ABOUT 50 TO ABOUT 90% BY WEIGHT OF THE MONOALKENYL SUCCINIC ACID ANHYDRIDE AND FROM ABOUT 10 TO ABOUT 50% BY WEIGHT OF THE POLYMERIZED LINOLEIC ACID, AND SAID POLYMERIC ASHLESS DETERGENT BEING SELECTED FROM THE GROUP CONSISTING OF (1) THE COPOLYMER OF BUTYL METHACRYLATE, DODECYL METHACRYLATE, OCTADECYL METHACRYLATE, AND N-VINYL PYRROLIDONE HAVING A RATIO OF ALKYL METHACRYLATE TO PYRROLIDONE OF ABOUT 10:1 AND A MOLECULAR WEIGHT OF APPROXIMATELY 250,000, AND (2) THE COPOLYMER OF DODECYL METHACRYLATE, TRIDECYL METHACRYLATE, OCTADECYL METHACRYLATE, AND POLYETHYLENE GLYCOL MONOMETHACRYLATE HAVING A RATIO OF ALKYL METHACRYLATE TO POLYGLYCOL METHACRYLATE OF ABOUT 100:1 AND A MOLECULAR WEIGHT OF ABOUT 350,000. 